The present invention relates to an alarm system capable of warning persons in the surrounding area of the potential outbreak of a fire.
With an increasing concern for safety, numerous fire alarms have been developed to provide immediate warning signals to occupants of a building upon the outbreak of a fire. Such alarms typically are electrically operated and are set off by sensing smoke within the area surrounding the alarm. Since the creation of such smoke normally only occurs once a fire has already broken out or as an immediate precursor to the fire, such alarms provide a relatively late warning signal. This drawback of these fire alarms that respond to smoke is particularly acute in large buildings where the fire can rapidly spread through the air duct system before the alarms are activated.
These types of fire alarms also are significantly deficient in certain locations where there are chemicals that release dangerous fumes when subjected to high temperatures. In such situations the mere presence of temperatures above certain levels can create a major safety hazard before any type of fire has broken out or even smoke created.
The fire alarms that are marketed today operate based on the principle of sound. Upon being activated, these alarms emit a loud buzzing or ringing noise readily detectable by persons in the surrounding area. Such alarms, however, serve no purpose if the occupants of the area are deaf.
Various types of alarms that emit warning signals relying upon the sense of smell have been developed for certain specific purposes. Examples of such alarms are shown in the patents to: Scribner, U.S. Pat. No. 2,065,614; Van Dyken, U.S. Pat. No. 1,052,392; Gannon, U.S. Pat. No. 1,755,642; and Timken, U.S. Pat. No. 2,026,807. The heat alarms disclosed by these patents are built into various types of machinery for releasing an odoriferous fluid when the machinery overheats beyond the preselected point or when a crack in such machinery occurs, which may be as a result of overheating. U.S. Pat. No. 2,711,709 to Sullivan discloses an alarm that produces an odor and smoke for use in railway car journal boxes for detecting overheating of the journals.
U.S. Pat. No. 4,015,015 to Knowles discloses a flammable substrate having bound thereto a nonvaporous organic material. The organic material on the substrate vaporizes when subjected to temperatures about 200.degree. C. and then creates a respiratory irritant. As pointed out in the patent to Sullivan numerous lives are lost each year due to high carbon monoxide levels or low oxygen levels instead of as a direct result of a fire itself. The alarms in existence often depend upon the creation of heavy smoke. Prior to the acitvation of such alarms, however, lethal quantities of carbon monoxide and other combustible products can quickly develop while the fire remains undetected.
In addition, most alarms depend upon receipt of electricity either from the electrical system within the building or from batteries. If an electrical fire is the main cause of the fire then the electricity may be terminated before the fire alarm is ever activated. With respect to the battery operated systems, the batteries normally need to be replaced on a periodic basis, normally at least once a year. If the battery wears down then until the battery is replaced the alarm is rendered inactive.